Soul Stone (5e Equipment)
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Wondrous Item, rare (requires attunement)
The soul stone can look like any precious stone or gem. If the stone is on your person, and you drop unconscious, you can roll an amount of Hit Dice equal to a third of your level rounded up (level 10 would get 4 dice) or half of your level rounded down when on holy ground (level 9 would get 4 dice), to regain that many hit points. This effect may be used once, and the soul stone regains use of this effect at dawn.
While attuned to this item, your soul is imbued in this stone which has 50 hp (recovered at dawn) and 12 AC. If the stone is destroyed, your alignment will become chaotic evil, even if your race, class, or background would usually forbid that.